Y. Mahrer
Control of grey mould depends on fungicide applications, because severe epidemics can be expected when conditions in greenhouses favour the disease. Microclimatic conditions which affect epidemics were characterised in unheated polyethylene greenhouses to investigate the possible introduction of non-chemical control methods for use with cucumber crops. From 14 to 9 days before the appearance of symptoms, plants were predisposed to the disease by low (< 9 C) and high (> 24 C) temperatures and by dryness. Infection occurred 7-8 days before symptoms were visible and was promoted by high humidity (> 91% rh) and temperatures in the range of 9-2 4 C. After infection took place, the infective mycelium was relatively protected by the host tissue and temperature and rh requirements were less stringent. A model based on qualitative analysis of the relationships between microclimatic factors and fruit or stem infections was developed. The two important parameters associated with outbreaks of epidemics were the duration of leaf wetness and the duration of night time temperatures between 9 and 21 C. The daily averages for the thresholds were 7 h per day for the wet period and 9.5 h per day for the duration of specific temperatures.
The nutritional and hormonal status of host plants also affected their susceptibility to development of grey mould epidemics. High humidity restricted movement of calcium to upper plant parts and calcium enrichment of host tissue reduced the susceptibility of pepper, tomato and eggplant to grey mould. Application of auxin to enhance fruit setting of eggplant reduced their susceptibility to the disease. In order to …
Y. Mahrer
Control of grey mould depends on fungicide applications, because severe epidemics can be expected when conditions in greenhouses favour the disease. Microclimatic conditions which affect epidemics were characterised in unheated polyethylene greenhouses to investigate the possible introduction of non-chemical control methods for use with cucumber crops. From 14 to 9 days before the appearance of symptoms, plants were predisposed to the disease by low (< 9 C) and high (> 24 C) temperatures and by dryness. Infection occurred 7-8 days before symptoms were visible and was promoted by high humidity (> 91% rh) and temperatures in the range of 9-2 4 C. After infection took place, the infective mycelium was relatively protected by the host tissue and temperature and rh requirements were less stringent. A model based on qualitative analysis of the relationships between microclimatic factors and fruit or stem infections was developed. The two important parameters associated with outbreaks of epidemics were the duration of leaf wetness and the duration of night time temperatures between 9 and 21 C. The daily averages for the thresholds were 7 h per day for the wet period and 9.5 h per day for the duration of specific temperatures.
The nutritional and hormonal status of host plants also affected their susceptibility to development of grey mould epidemics. High humidity restricted movement of calcium to upper plant parts and calcium enrichment of host tissue reduced the susceptibility of pepper, tomato and eggplant to grey mould. Application of auxin to enhance fruit setting of eggplant reduced their susceptibility to the disease. In order to …